https://www.theguardian.com/commentisfr ... reme-court
TL;DR if they decide in line with the independent state legislature theory, states would be legally allowed to tamper with their electoral votes, with the courts being able to do nothing. Likewise for any other kind of state-level tampering in federal elections. No more Democratic Presidents ever, and the Republicans would quickly retake both the House and Senate.
Edit: and yes, timing this right before the 2022 elections is obviously deliberate.